Changes

===Spectral class Y===

===Spectral class Y===

Y dwarfs are believed to be even cooler than T dwarfs, and are considered theoretical.<ref>http://xxx.lanl.gov/abs/astro-ph/0607305</ref>  Such dwarfs would have surface temperatures under 700K.  In March 2008, a brown dwarf called CFBDS J005910.90-011401.3 was discovered, which a surface temperature of only 620K, and is believed to be the first such Y dwarf found.<ref>http://arxiv.org/abs/0802.4387</ref>

Y dwarfs are believed to be even cooler than T dwarfs, and are considered theoretical.<ref>http://xxx.lanl.gov/abs/astro-ph/0607305</ref>  Such dwarfs would have surface temperatures under 700K.  In March 2008, a brown dwarf called CFBDS J005910.90-011401.3 was discovered, which a surface temperature of only 620K, and is believed to be the first such Y dwarf found.<ref>https://arxiv.org/abs/0802.4387</ref>

==Detecting brown dwarfs==

==Detecting brown dwarfs==

The most significant indicator used to differentiate between brown dwarfs, and very low mass, cool [[red dwarf]]s is the presence of [[lithium]], often referred to as the ''Lithium test''.  This is due to red dwarf stars having sufficient temperature to quickly deplete any lithium available, which occurs when lithium-7 and a proton collide to produce two helium-4 atoms. As red dwarfs transport energy to the surface entirely through convection, all the lithium in the star is converted over time.  Normally, brown dwarfs lack the mass and temperature to exhaust the available lithium, however higher mass brown dwarfs of .0065 solar masses or greater, have sufficient temperature to also expend their lithium (which is slightly lower than the temperature required to fuse hydrogen), abet over a longer period of time.<ref name="bdref"/>

The most significant indicator used to differentiate between brown dwarfs, and very low mass, cool [[red dwarf]]s is the presence of [[lithium]], often referred to as the ''Lithium test''.  This is due to red dwarf stars having sufficient temperature to quickly deplete any lithium available, which occurs when lithium-7 and a proton collide to produce two helium-4 atoms. As red dwarfs transport energy to the surface entirely through convection, all the lithium in the star is converted over time.  Normally, brown dwarfs lack the mass and temperature to exhaust the available lithium, however higher mass brown dwarfs of .0065 solar masses or greater, have sufficient temperature to also expend their lithium (which is slightly lower than the temperature required to fuse hydrogen), abet over a longer period of time.<ref name="bdref"/>

For the coolest and least massive brown dwarfs, the main method to distinguish them from large gas giants is density. Even though all brown dwarfs are around the same radius, which is close to the radius of the largest gas giants, they are many times more massive, and thus more dense.  Typically the higher volume of a brown dwarf is controlled through [[electron degeneracy]], although the least massive brown dwarfs' volume is controlled through [[Coulomb pressure]].<ref>http://arxiv.org/abs/astro-ph/0608417</ref>   

For the coolest and least massive brown dwarfs, the main method to distinguish them from large gas giants is density. Even though all brown dwarfs are around the same radius, which is close to the radius of the largest gas giants, they are many times more massive, and thus more dense.  Typically the higher volume of a brown dwarf is controlled through [[electron degeneracy]], although the least massive brown dwarfs' volume is controlled through [[Coulomb pressure]].<ref>https://arxiv.org/abs/astro-ph/0608417</ref>   

[[Category:Astronomy]]

[[Category:Astronomy]]